1. Field of the Invention
The invention relates to circular cutter shears for the longitudinal edging of plates and sheets.
2. Description of the Prior Art
In known circular cutter shears for edging plates, in order to achieve straight and rectangular cut edges one of the circular cutter shafts is inclined with respect to the surface of the plate, while the other circular cutter shaft is mounted horizontally.
This arrangement of the circular cutters has the disadvantage that the cutter clearance changes in the cutting engagement, so that on account of the narrowing of the cutter clearance the cutter is scraped on the cut edge and thus increased cutter wear occurs and inexact cut edges are produced.
The object of the invention is to avoid the disadvantages of the known circular cutter shears. A more specific object is to provide circular cutter shears of simple design and operation, with which straight and rectangular cut edges are made possible and wear of the cutter shaft bearings and the circular cutters on account of the narrowing of the cutter clearance and jamming is prevented.
This object is attained according to the invention in that the circular cutter shaft inclined towards the surface of the plate is swung with its end remote from the cutter through an angle .beta. opposite the direction of feed of the plate. Thus, the rotation plane of the inclined cutter diverges from the said direction or the cut edge by the said angle.
This invention also provides shears for trimming the longitudinal edges of plates and sheets, comprising an upper circular cutter and a lower circular cutter defining therebetween a cutting gap for receiving a plate or sheet to be trimmed fed between the cutters, a lower cutter shaft carrying the lower cutter, mounted horizontally and transversely to the feed direction of the plates and sheets, and an upper cutter shaft which carries at an end thereof the upper cutter, the upper cutter shaft being inclined obliquely at an acute angle relative to the lower cutter shaft when seen in the feed direction, and therefore relative to the plate or sheet surface, the upper cutter shaft also being disposed obliquely relative to the feed direction whereby the axis of the shaft forms an acute angle of offset relative to a direction perpendicular to the feed direction.
The offset angle .beta. ensures that the circular cutting edge of the cutter runs free from the cut edge of the plate and that the edging strips are spread apart. The offset angle .beta. can amount for example to from 0.5 to 1.degree. in the case of an angle of inclination .alpha. of 6.degree..
A particularly simple design of the circular cutter shears is achieved by the upper inclined cutter shaft being mounted non-displaceably and rotatably and the horizontally mounted lower cutter shaft being mounted in such a way as to be vertically adjustable. In this construction the adjustment of the cutter clearance is effected at the same time as the circular cutter disposed on the horizontally mounted cutter shaft is set to the plate thickness. It is not necessary to set the circular cutters in the axial direction.
Alternatively both upper and lower cutter shafts are vertically adjustable. By this means both a planar and a radial cutter grinding are possible without alteration of the angle of inclination.
The cutter shafts are advantageously mounted in adjustable eccentrics for plate thickness setting.
In the case of the shears according to the invention a predetermined angle of inclination .alpha. and offset angle .beta. can be provided in a structural form for the plate thickness range to be cut. For the purpose of adjustment to different plate thicknesses over a larger plate thickness range, however, the angle of inclination .alpha. and/or the offset angle .beta. can be made adjustable in operation.
In a further development of the invention a circular cutter shaft is stepped towards its end beyond a receiving pin for the circular cutter, and a stop ring, against whose annular surface projecting beyond the receiving pin the circular cutter can be clamped, and can be held against the lateral step surface.
In this way a circular cutter fastening is produced which is not affected by cutter wear.
Threaded nuts or hydraulic nuts can be provided as clamping elements for the circular cutters.